[combat1]

Absolutely stumped!
Upgraded my ro system by fitting the correct booster pump for a 300gpd system.
I have two 150 membranes one on top of the other.
when I switch the new pump on the filter canisters level drops, meaning I have to unscrew them to release the air.
This keeps happening. will run for a bit then the level drops again.
I put the old pump back on, quiet as a mouse and ran with no problems.
Checked all my connections, run it for an hour without the pump, checked water into pump etc etc.

Suppliers have been brilliant, I have tried all their suggestions.
I've tried the pump in all directions upright and horizontal but still keeps happening.
It means I cant leave the system.
When running the new pump is at 60psi and water production is so much faster, the old pump was 40 psi and a lot slower.
Any ideas would be really appreciated as I have had to go back to the old pump at the moment and my upgrade is not happening £90+ on the new pump!
thanks guys

[Don Kee]

What do you mean by the filter level dropping?
You're getting no watee supply, or you're getting an airlock?

Where is the pump fitted?if you havent already, try in between the prefilters and membranes

[combat1]

Hi, The water level drops presumably air, as soon as I unscrew the filter housing it fills again.
You could see in the pipe from the pre filters to the pump air and water together.
The pump is located after the pre filters and as near to the membrane as poss.
Pressure guage shows a good 60psi going into the membrane.
But cannot run the pre filters with half empty vessels.
If left it just gets worse, at the start its the sediment filter that drops, if left the carbon filter also starts to drop.

Really baffling, been a week of mucking about!

[Don Kee]

If you prefilters are before the pump, and its the prefilters that are lacking water are you sure its the pump that's the problem?

When your prefilters starts to lack water, where does the water go?(are you busting a pipe anywhere?there no waste on the prefilters so the inlet water needs to go somewhere...)

[paulben]

I get same problem make sure there are no air leaks in connections that are sucking air into system When I get a prob I just remove pipe on inlet side and run water til it runs without air coming through

[combat1]

Some water must be getting through because its still producing pure even when the level drops in the vessels, think they draw up through the centre of the filter.
I disconnect the pipe from the inlet of the pump and let the water flow before reconnecting,
When I swopped back to the original pump there was no problem at all.

[Frankybadboy]

try plumbing in the pump after the prefilters and try that 

[combat1]

Thanks Franky, the pump has always been after the pre filters and close to the membrane.
Real puzzler to put it nicely, going to take some time away from it, have made my water for the week so going to have a break and come back to the problem afresh.
If I don't solve it then I will just revert to the old 40psi pump which works ok.

[SeanK]

If I'm reading this right then your pump is pumping faster than the mains can supply it, check to see
if there is a blockage from the mains to the pre filters.
Try putting the pump before the pre filters and as close to the tap as possible.

[AuRavelling79]

All other things being equal - connectors on the new pump correct etc. - it's got to be the 20psi difference that is causing the problem. Not much help sorry.

[slap bash]

What does your pump deliver in liters. It sound like your tap flow is to low and sucking in aire into the system before the pump.

[combat1]

I think you are right guys!
My incoming water pressure is 20psi
Sounds low to me!
Supposing I put the old 40 psi pump before the prefilters and kept the new 60 psi pump before the membrane
Do you reckon this would be ok.
Would the increased pressure be ok for the filters?
The extra cost of electric would be worth it as at 60psi it is so fast producing and I could leave the system running on the timeswitch.
Cheers guys.

[robert mitchell]

Its the flow rate from your tap that is more important for your problem , you can measure this by using your outside tap to fill a litre bottle and time it .

does your outside tap have a double check valve built in ?

they restrict the flow a lot so i removed mine .

[combat1]

Maybe not as easy as I thought then!
I will measure the flow rate tomorrow in the light.
I have a sub meter between the tap and the pre filters, would this affect the flow rate?
Thanks

[dannymack]

Hiya combat I have my pump before my prefilters but make sure when your screwing the prefilters canisters up that the filters are sitting right as this happened to me and I was puzzled as I kept pulling the pipe off that goes into the ro spraying water everywhere and then push it back in quick where the water would go fast agin for abit. When I changed my prefilters to new ones one of the old filter was sqaushed at the top where it wasn't sitting right when I screwed the canister up
Just a thought try new pre filters

[combat1]

Hi Dannymack
I will check my filters later. I did change them when i fitted the new pump. Maybe the sediment one is displaced. Thanks for the advice.
got quite a topic going now!

[Frankybadboy]

right my second thought

the pipe going from tap to membraines,is it 1/2inch or is it the tubing (same size as on the ro)

??

also go to your stop tap out in the road and turn it up if you can

[combat1]

Pipe from tap to sub meter  1/2 inch then about 15 feet of 1/4 inch tube.
Always been fine before and still ok for the 40 psi pump.
What a to do ha ha.

[Don Kee]

Defo check your prefilters are seated properly mate

[combat1]

Well guys! Bet you are all waitin with crossed legs to hear the outcome.
Firstly a great big massive thank you for all your help, was nearly goin bananas.
So, took advice! Changed pipe from tap to unit to 1/2 inch.
(Noticed water spraying out of a tiny hole in the old pipe)
Changed the filters
Relocated the new pump so that it was before the prefilters.

Result:
200 litres in just over 4 hrs. A huge improvement.
Constant 60 psi .
No problems at all
Many thanks for all your contributions, big result for CIU.